The shortage of pure drinking water is rapidly becoming a serious problem. Currently available methods for purifying water from natural and reclaimed sources are generally incapable of removing certain chemicals and biologically active substances that are appearing in water supplies in alarmingly increasing proportions. It appears that biologically active substances that are intentionally or accidentally dumped into our ponds, streams and rivers or enter ground strata via septic systems could become potentially dangerous substances when the water from these sources is treated by conventional means and is eventually used for drinking.
Standard methods for purifying water such as coagulation, sedimentation, filtration and chemical treatment are effective for removing most contaminants and for killing most of the microorganisms present. These methods, however, are not completely effective for removing substances such as hormones, pesticides, viruses, toxins and heavy metal cations. The use of female steroids for birth control purposes, for example, and growth hormones for fattening-up beef and poultry, has resulted in significant quantities of these hormones finding their way into municipal water supplies, particularly in large metropolitan areas.
Methods for the treatment of sewage, such as removal of solids by flocculation followed by sedimentation and centrifuging, and removal of bacteria by chemical treatment are generally ineffective for removing hormones and viruses. When the "harmless" liquid effluents from sewage treatment plants are dumped into inland waters these hormones are still present in the water. When inland waters are subsequently used as backups for water reservoirs and other storage facilities for municipal water supplies, these intractable contaminants end up in water that is used for drinking purposes. Subsequent purification procedures are generally incapable of removing these hormones so that it is possible for them to enter the human body along with the drinking water. The same problem, in more or less increasing proportions, is true for other substances such as viruses, toxins, heavy metal cations and pesticide residues.
Another potential source contributing to the human self-contamination cycle is the backyard swimming pool. Viruses, toxins and hormones which are deposited in these backyard pools gradually increase in concentration since they are generally immune to the effects of routine filtering and chemical treatment. When the pools are eventually emptied these biologically active substances could conceivably reach the bathroom and kitchen water taps. This is particularly true for large inland municipalities where the effluents from sewerage treatment plants cannot be discharged directly into the sea from which the possibility of return is extremely remote.
The purpose of this invention, therefore, is to provide methods and materials for removing potentially harmful substances which are generally immune to standard sewage treatment and water purification processes from waste streams and/or potable water.